This invention pertains to floor jacks and more particularly to a floor jack adapted to lift relatively heavy automotive equipment such as truck tractors or semi-trailers. Customarily this type of equipment is lifted by hydraulic jack equipment, but use of conventional equipment has become increasingly difficult because of the structure of the equipment to be lifted.
The point of application of the jacking pad atop the ram of the jack to the equipment to be raised is a particular problem. On occasion this point of application may be the axle near a wheel to be worked on. However with tandem axles, the particular axle to be used may be effectively hidden.
Applying this jack to a portion of the leaf spring is virtually impossible because that spring is usually lying at a slope to the floor and therefore the jack has a tendency to slip, or the horizontal component of force on the sloping spring may cause the trailer to roll away, thus creating havoc.
The best point on which to jack is usually a frame member of the tractor or trailer. However, this framework is usually directly above the leaf springs and is difficult for a vertical jack to reach.
By the present invention, the jack is modified so as to be able to be used either with an extension to reach the frame member adjacent the spring or, where available, to be placed directly under a vertical point of application.